One of my students created this pattern to have eggbot draw a face

My fascination with motion control began with this simple device-- a
two axis egg plotter (see right). I had just learned how to control two stepper
motors, and needed some way of demonstrating just how interesting this
capability is. The success of this experimental "eggbot" not
only spurred me on to build bigger two-axis machines, but evolved into
an educational tool-- I now teach kids to build their own eggbots, using
a course I am continually expanding: "From
Bits to Bytes... to Bots"